1. Field of the Invention
This invention relates to laundry machines, and more particularly to a combination drain sump and air pressure chamber used in automatic clothes washers.
2. Description of the Prior Art
Automatic clothes washing machines have had drain sumps which act as foreign object traps to prevent rigid items such as hair pins, buttons, etc., from being introduced into the pump mechanism during pumpout of the machine. These items can be harmful to the pump and on many occasions actually cause the pump to fail. One such prior art foreign object trap assembly is shown in U.S. Pat. No. 3,590,606.
Automatic clothes washing machines have also included a water supply system that regulates the amount of water introduced into the machine during the fill period by having an air pressure responsive means controlling a valve for stopping the introduction of water when a predetermined level is reached. One such prior art system uses a pressure sealed sump having an integral air trapping chamber in which air is compressed directly in proportion to the amount of water being introduced into the washing machine tub. See for example U.S. Pat. No. 3,367,153. When the air pressure reaches a certain value and a pressure responsive switch is actuated in response to that value, the water inlet valves are turned off. As an example of one such pressure responsive switch, see U.S. Pat. No. 2,934,618. One of the difficulties with such a pressure actuated liquid level responsive arrangement is that the very small diameter tubing leading from the air chamber to the pressure responsive switch is easily blocked by suds causing malfunction of the system. The suds are present in the system as a result of the previous pumping out operation of the wash water as the system cannot be completely evacuated.
By my invention, I have provided a combination drain sump that acts as a foreign object trap and an air pressure chamber member that will prevent blockage of the air pressure between the air chamber and the pressure responsive switch.